The present invention relates to a directional illumination energy-saving luminaire using light-emitting diodes (LEDs), and more particularly, it pertains to a LED directional illumination energy-saving luminaire for roads lighting, that adopts LEDs having small projection angles and being slantwise mounted at a predetermined angle as light-emitting elements, and is capable of achieving an accurate directional illumination, a well lighting effect, an energy-saving effect, and a well performance of heat dissipation. The present invention also relates to a method for manufacturing said LED directional illumination energy-saving luminaire.
A LED luminaire is a kind of high efficiency, energy-saving luminaire that has an ultra-long service life, currently utilized in many areas, for example, street lighting, industrial lighting, stage lighting, landscape decorative lighting, and indoor lighting.
As is well-known, with respect to street lamps for the lighting of the road surface such as highroad, express highway, urban street and the like, to minimize effects of glare on the driver, it is necessary to use cut-off luminaires that are designed and manufactured according to national standards for the design of street lighting and have an angle of light projection of 120 degrees, such as those which are made by providing a reflex lampshade with the conventional flood-type street lamps like the high-voltage sodium lamps etc., and that have a light projection angle of 120 degrees. Presently, the lighting street lamps using LEDs applied in the field of road lighting, for the purpose of meeting the requirements by national standards for the design of street lighting, mostly are such luminaires that are made by adopting the LED with a large light projection angle as the light-emitting elements and that have a projection angle of 120 degrees.
The deficiencies of the conventional lighting street lamps are as follows:
With the conventional lighting street lamp, a large portion of the illumination emitted by the light source thereof is projected onto the outside of the road surface that needs no lighting, while the road surface that does need lighting can merely receive a luminous flux that is less than half of the total amount of illumination given by the light source. Thus the utilization ratio of lamp illumination is very low, resulting in the loss of light and the waste of electric energy. In addition, the illumination that is projected outside of the road surface may even further give rise to an undesirable light pollution. Hereinafter, a detailed description will be set forth with reference to the schematic views. As shown in FIG. 1 and FIG. 2, the lighting street lamp 1 is mounted on the lamp post 101, for lighting the road surface of the street 102. The projection angle of the street lamp 1 is 120 degrees, the encircled portion 103 represents an area of a projecting circular region of the lamp 1, a hatched portion 104 represents an area of the road surface that is illuminated by the lamp 1, i.e., the actually utilized portion of the projected light, and a hatched portion 105 represents the area of the outside of the road surface that is illuminated by the lamp 1, i.e., the wasted portion of the projected light. From the above mentioned schematic views, it can be clearly seen that, the wasted portion of the light due to the illumination onto the outside of the road surface occupies a significant proportion in the luminous flux projected by the light source. In the table below, relevant data are listed for the street lamps which have a mounting height of 5-12 meters and are utilized for the lighting of roads with a width of 6-10 meters.
MountingArea of lampArea of roadheight ofWidth ofilluminationsurfacestreetroadIlluminatingcircleilluminatedUtilizationlampsurfaceradius(square(squareratio of lamp(meter)(meter)(meter)meter)meter)illumination568.66235.62103.9244.11%6610.39339.29124.6836.75%7812.12461.81193.9241.99%8813.86603.19221.7036.76%91015.59763.41311.7740.84%101017.32942.48346.4136.76%111019.051140.40381.0533.41%121020.781357.17415.6930.63%
In conventional LED lighting street lamps, since a reflex lampshade is adopted for reflecting light, the illumination is uneven, the illuminating intensity directly under the luminaire is relatively high, while the illuminating intensity far from the luminaire is relative low. The ununiformity of road surface lighting is prone to having a disadvantageous influence to the driver, giving rise to risks of traffic accidents.
In the conventional LED lighting street lamps, since LEDs with large projection angles are adopted, the phenomenon of light scattering is serious, the capability of transmission is weak, the mounting height is limited, and it is difficult to achieve a long distance illumination.
In the conventional LED lighting street lamps with high power, there is a great amount of heat generated during working of the LED which would not easily dissipate outside, and there lacks an effective structure for heat dissipation, thus temperature of the LED rises quickly, so the luminous efficiency thereof is reduced and the service life thereof is shortened.